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NTSB CITES HUMAN FATIGUE AND POSITIVE TRAIN CONTROL IN 2008 TROLLEY COLLISION THAT KILLED ONE



Title: NTSB CITES HUMAN FATIGUE AND POSITIVE TRAIN CONTROL IN 2008 TROLLEY COLLISION THAT KILLED ONE

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                      NTSB PRESS RELEASE
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National Transportation Safety Board
Washington, DC 20594

FOR IMMEDIATE RELEASE: July 14, 2009
SB-09-37

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NTSB CITES HUMAN FATIGUE AND POSITIVE TRAIN CONTROL IN 2008
TROLLEY COLLISION THAT KILLED ONE

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WASHINGTON, D.C. - The National Transportation Safety Board
today determined that the two-train collision on the
Massachusetts Bay Transportation Authority (MBTA) Green Line
last year occurred as a result of the trolley operator's
failure to obey a signal indication likely because she
became disengaged from her environment consistent with
experiencing an episode of micro-sleep. The lack of a
positive train control system, which would have intervened
to stop the train and prevented the collision, was cited as
a contributing factor.

At 5:51 PM EDT, on May 28, 2008, an MBTA Green Line train,
traveling westbound at about 38 mph, struck the rear of
another westbound Green Line train, which had stopped for a
red signal. The operator of the striking train was killed;
three other crewmembers sustained minor injuries. Of the 185
to 200 passengers who were on the two trains at the time of
the collision, four sustained minor injuries and one was
seriously injured. Total damages were estimated to be about
$8.6 million.

Post-accident toxicological testing indicated that the
operator of the striking train had recently taken the drug
doxylamine, commonly found in sleep aids, suggesting that
she had trouble sleeping during at least one of the nights
leading up to the accident.  In addition, the operator had a
high body mass index (BMI), which is closely correlated with
a higher risk for sleep apnea, increasing the likelihood of
a fatigued condition during waking hours.

NTSB Acting Chairman Mark V. Rosenker highlighted the role a
positive train control system could have played in
preventing the accident.  "Again, we've seen a situation
where a positive train control system could have prevented a
tragic accident," said Rosenker. "We know that because
operators or equipment sometimes fail, redundancies like PTC
systems can be the difference between a fatal accident and
an incident report. And this is why we feel so strongly that
transit systems like MBTA's should have that crucial extra
layer of safety that a PTC system provides."

Because the Safety Board concluded that the accident could
have been prevented had the MBTA been equipped with a
positive train control system, the NTSB recommended to the
Federal Transit Administration that the agency facilitate
the development and implementation of positive train control
systems for rail transit systems nationwide.

As a result of its investigation of a transit system
accident in Maryland in 2000, the Safety Board recommended
in 2001 that MBTA establish a fatigue awareness program to
addresses potential sleep disorders among its train
operators.  While the MBTA indicated that they had
established and implemented such a program, the Safety Board
determined that their efforts were inadequate and reiterated
that safety recommendation.

In addition, the NTSB recommended to the Federal Transit
Administration (FTA) that they develop and disseminate
guidance for operators, transit authorities, and physicians
regarding the identification and treatment of individuals at
high risk for obstructive sleep apnea and other sleep
disorders.

The Safety Board recommended to MBTA that train operators be
required to notify fellow crewmembers when a restrictive
signal is encountered, and the intended means of complying
with the restriction.

And because MBTA operating rules do not require train
operators to report signals displaying red when the track is
visibly clear, the NTSB has concluded that this could allow
possible problems in the signal system to remain undetected
and unrepaired, which could increase safety risks. Thus, the
Safety Board recommended to MBTA that train operators
immediately report all red signals they encounter when the
track governed by that signal can be seen to be clear of
other trains.

A summary of the findings including the Board's report is
available on the NTSB's website at
http://www.ntsb.gov/Publictn/2009/RAR0902.html

The entire accident docket is available at
http://www.ntsb.gov/Dockets/Railroad/DCA08MR007/default.htm


# # #

NTSB Media Contact: Peter Knudson
(202) 314-6100
peter.knudson@xxxxxxxx

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